Coquinas accumulate in high-energy marine and lacustrine environments where currents and waves result in the vigorous winnowing, abrasion, fracturing, and sorting of the shells, which compose them. As a result, they typically exhibit well-developed bedding or cross-bedding, close packing, and good orientation of the shell fragments composing them. The high-energy marine or lacustrine environments associated with coquinas include beaches, shallow submarine raised banks, swift tidal channels, and barrier bars.[4][5]

Contents

Coquina is mainly composed of the mineralcalcite, often including some phosphate, in the form of seashells or coral. Coquinas dating from the Devonian period through to the much more recent Pleistocene are a common find all over the world, with the depositional requirements to form a coquina being a common thing in many marine facies.

Occasionally quarried or mined and used as a building stone in Florida for over 400 years, coquina forms the walls of the Castillo de San Marcos, Saint Augustine. The stone makes a very good material for forts, particularly those built during the period of heavy cannon use. Because of coquina's softness, cannonballs would sink into, rather than shatter or puncture, the walls of the Castillo de San Marcos.

Sedgely Abbey, an 18th century manor house once regarded as the grandest colonial residence on the lower Cape Fear River in North Carolina was built of locally quarried coquina. Once the centerpiece of a 1,000 acre (405 hectare) plantation that produced indigo and rice its name was derived from the ancient manor of Sedgely in Staffordshire. Located a half-mile north of Snow's Cut, directly across the river from Orton, the house was a two story, five bay, center hall, single pile, Georgian structure, with a chimney at each end. Although its builder is unknown, it was described as similar in size and appearance to the brick mansion built in 1825 by Governor Dudley that still stands at 400 South Front Street in Wilmington. Like many southern plantations, Sedgely Abbey was abandoned and fell into disrepair after the Civil War. The vacant house was demolished in the 1870s and the coquina was made into fertilizer. A cellar carved into solid coquina was located during archaeological investigations on the site of the former plantation in the late 20th century.

When first quarried, coquina is extremely soft. This softness makes it very easy to remove from the quarry and cut into shape. However, the stone is also at first much too soft to be used for building. In order to be used as a building material, the stone is left out to dry for approximately one to three years, which causes the stone to harden into a usable, but still comparatively soft, form.

Coquina has also been used as a source of paving material. It is usually poorly cemented and easily breaks into component shell or coral fragments, which can be substituted for gravel or crushed harder rocks. Large pieces of coquina of unusual shape are sometimes used as landscape decoration.

Because coquina often includes a component of phosphate, it is sometimes mined for use as fertilizer.